Methods for fabricating a structural beam

ABSTRACT

A method for fabricating a structural beam having a cross-sectional profile. First portions of the profile being in compression and second portions of the profile being in tension due to a loading force. The beam also having compressive and tensile structural elements. Each structural element includes an enclosure having walls, and a non-compressible material disposed in their cavity. The walls of the compressive structural elements each have at least a portion thereof inwardly shaped towards the first cavity such that when deflected by the loading force, the walls exert a compressive force against the non-compressible material in its cavity, resulting in a resistance to the deflection and the loading force. The walls of the tensile structural elements each have at least a portion thereof outwardly shaped away from the second cavity such that when deflected by the loading force, the walls exert a compressive force against the non-compressible material in its cavity, resulting in a resistance to the deflection and the loading force. The method includes the steps of: providing the compressive structural elements; providing the tensile structural elements; forming the beam having the cross-sectional profile to a predetermined length; and during the forming, disposing a multiplicity of the compressive and tensile structural elements throughout the beam cross-sectional profile and along the predetermined length. Another method joins the compressive and tensile structural elements together to form the structural elements which are then disposed throughout the beam cross-sectional profile and along its length.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 08/934,402, filedSep. 19, 1997 now U.S. Pat. No. 6,054,197.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of art to which this invention relates is structural elements,and more particularly to lightweight structural elements having a cavityin which a non-compressible material is disposed resulting in a rigidstructure and/or one capable of vibration damping.

2. Description of the Related Art

It is highly desirable to build high speed machinery which are veryaccurate with structural elements that are light weight, have a highdegree of stiffness, and have high internal damping characteristics.This is in fact the case for any product that is subjected to internallyand/or externally induced vibrational excitation. With such structuralelements, one can then design machines, structures, and other similardevices that are very accurate, that are lighter, and that can operateat higher speeds. This leads to a significant increase in performance.

In the prior art, when vibration becomes a factor, designers had theoption of either adding various combinations of mass and viscoelasticmaterial to the structure to employ a passive damper or employ some typeof active damping device, such as a piezoelectric device. While theprior art passive damping devices have their advantages, they sufferfrom the disadvantage of greatly increasing the weight of the structure.This results in a reduction in the attainable speed of the machine ordevice. Active dampers, on the other hand, are usually lighter butgreatly increase the cost of the machine as well as the cost of itsoperation.

For the above reasons, there is a need in the art for a low weight, lowcost structural element that is very rigid and has high internaldamping.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a lightweight structural element.

It is a further object of the present invention to provide a low coststructural element.

It is yet a further object of the present invention to provide a lightweight structural element that provides for increased rigidity overcomparable weight structural elements.

It is still yet a further object of the present invention to provide astructural element that is light weight and has high internal damping.

Accordingly, structural elements are disclosed, wherein a firstembodiment has an enclosure having walls surrounding a cavity, and anon-compressible material disposed in the cavity. The walls are shapedsuch that a force tending to compress the element by a first deflectioncauses an amplified second deflection of the walls into thenon-compressible material. The second deflection exerts a compressiveforce against the non-compressible material, resulting in a resistanceto the first deflection and the force tending to compress the element.

In a second embodiment, the structural element has an enclosure havingwalls surrounding a cavity, and a non-compressible material disposed inthe cavity. The walls are shaped such that a force tending to elongatethe element by a first deflection causes an amplified second deflectionof the walls into the non-compressible material. The second deflectionexerts a compressive force against the non-compressible material,resulting in a resistance to the first deflection and the force tendingto elongate the element.

In a third embodiment, the structural elements of the first and secondembodiments are combined where a first enclosure having first wallssurrounding a first cavity is provided. A second enclosure having secondwalls surrounding a second cavity is also provided. The structuralelement further has a first non-compressible material disposed in thefirst cavity, and a second non-compressible material disposed in thesecond cavity. The first walls are shaped such that a first forcetending to compress the element by a first deflection causes anamplified second deflection of the first walls into the firstnon-compressible material, exerting a first compressive force againstthe first non-compressible material, resulting in a resistance to thefirst deflection and the first force tending to compress the element.The second walls are shaped such that a second force tending to elongatethe element by a third deflection causes an amplified fourth deflectionof the second walls into the second non-compressible material, exertinga second compressive force against the second non-compressible material,resulting in a resistance to the third deflection and the second forcetending to elongate the element.

In a fourth embodiment of the present invention the structural elementof the first embodiment is configured into a cylindrical enclosurehaving a wall, a top, a bottom, and a cavity defined by the wall, topand bottom, the top and bottom being separated by a height. Thestructural element further having a non-compressible material disposedin the cavity. The wall is concavely shaped such that a firstcompressive force tending to decrease the height causes an amplifieddeflection of the wall into the non-compressible material, exerting asecond compressive force against the non-compressible material,resulting in a resistance to the amplified deflection and the firstcompressive force.

In a fifth embodiment of the present invention the structural element ofthe second embodiment is configured similarly to the fourth embodimentexcept that the wall is convexly shaped such that a tensile forcetending to increase the height of the structural element causes anamplified deflection of the wall into the non-compressible material,exerting a compressive force against the non-compressible material,resulting in a resistance to the amplified deflection and the tensileforce.

In variations of the fourth and fifth embodiments, the wall comprises aplurality of panels, the panels being separated by a flectural joint foraiding the deflection of the wall into the non-compressible material.

In variations of the above embodiments, the structural elements areconfigured for either optimum damping or optimum rigidity or acombination of rigidity and damping.

In yet other variations of the above embodiments, the structuralelements are disposed on, or in, structural beams configured for eitheroptimum damping, optimum rigidity, or a combination of rigidity anddamping.

In yet other variations of the above embodiments, the structuralelements are disposed on, or in, motion impartation devices configuredfor either optimum damping, optimum rigidity, or a combination ofrigidity and damping.

Another aspect of the present invention are methods of fabricating thestructural beam embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the apparatus andmethods of the present invention will become better understood withregard to the following description, appended claims, and accompanyingdrawings where:

FIG. 1A illustrates a front view of a first embodiment of the presentinvention;

FIG. 1B illustrates a side view of the embodiment of FIG. 1A;

FIG. 1C illustrates a sectional view of the embodiment of FIG. 1B takenalong line 1C--1C;

FIG. 2A illustrates a front view of a second embodiment of the presentinvention;

FIG. 2B illustrates a side view of the embodiment of FIG. 2A;

FIG. 2C illustrates a sectional view of the embodiment of FIG. 2B takenalong line 2C--2C;

FIG. 3A illustrates the sectional view of FIG. 1C deflecting under acompressive force;

FIG. 3B illustrates the sectional view of FIG. 2C deflecting under atensile force;

FIG. 4A illustrates a front view of a third embodiment of the presentinvention;

FIG. 4B illustrates a side view of the embodiment of FIG. 4A;

FIG. 4C illustrates a sectional view of the embodiment of FIG. 4B takenalong line 4C--4C;

FIG. 5A illustrates the sectional view of FIG. 4C deflecting under acompressive force;

FIG. 5B illustrates the sectional view of FIG. 4C deflecting under atensile force;

FIGS. 6A, 6B, and 6C illustrate versions of the first three embodiments,respectively, having a non-uniform wall thickness;

FIG. 7A illustrates a front view of a fourth embodiment of the presentinvention;

FIG. 7B illustrates a sectional view of the embodiment of FIG. 7A takenalong line 7B--7B;

FIG. 7C illustrates a sectional view of the embodiment of FIG. 7A takenalong line 7C--7C;

FIG. 8A illustrates a front view of a fifth embodiment of the presentinvention;

FIG. 8B illustrates a sectional view of the embodiment of FIG. 8A takenalong line 8B--8B;

FIG. 8C illustrates a sectional view of the embodiment of FIG. 8A takenalong line 8C--8C;

FIG. 9A illustrates an isometric view of a structural beam whereinstructural elements of the first and second embodiments are disposedalong its upper and lower surfaces;

FIG. 9B illustrates a partial view of FIG. 9A as viewed along line9B--9B;

FIG. 9C illustrates a partial view of FIG. 9A as viewed along line9C--9C:

FIG. 10A illustrates an isometric view of a structural beam whereinstructural elements of the third embodiment are disposed along its upperand lower surfaces;

FIG. 10B illustrates a partial view of FIG. 10A as viewed along line10B--10B;

FIG. 10C illustrates a partial view of FIG. 10A as viewed along line10C--10C:

FIG. 11A illustrates a front view of a sixth embodiment of the presentinvention;

FIG. 11B illustrates a sectional view of the embodiment of FIG. 11Ataken along line 11B--11B;

FIG. 12A illustrates a front view of a structural beam whereinstructural elements of the fourth and fifth embodiments of the presentinvention are disposed throughout the beam's cross-sectional profile;

FIG. 12B illustrates a sectional view of the beam of FIG. 12A takenalong line 12B--12B;

FIG. 13A illustrates a front view of a structural beam whereinstructural elements combining the fourth and fifth embodiments of thepresent invention are disposed throughout the beam's cross-sectionalprofile;

FIG. 13B illustrates a sectional view of the beam of FIG. 13A takenalong line 13B--13B;

FIG. 14A illustrates a front view of a motion impartation couplingcomprising structural elements of the present invention;

FIG. 14B illustrates a sectional view of the motion impartation couplingof FIG. 14A taken along line 14B--14B;

FIG. 15 illustrates a sectional view of a translating motion impartationdevice comprising structural elements of the present invention;

FIG. 16 illustrates a flow diagram outlining the steps for fabricatingthe structural beam of FIGS. 12A and 12B; and

FIG. 17 illustrates a flow diagram outlining the steps for fabricatingthe structural beam of FIGS. 13A and 13B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 1A, 1B, 1C, and 3A, there is illustrated a firstembodiment of the present invention, namely, a compressive structuralelement referred to generally by reference numeral 100. The compressivestructural element 100 has an enclosure 102 having walls 103, 104 anddefining a cavity 106. Walls 104 are preferably formed by extruding thestructural element's cross-sectional profile 105, as shown in FIG. 1C.Walls 103 are preferably plates, formed by conventional methods, such asstamping, and fastened to the cross-sectional profile by conventionalmethods, such as welding. However, walls 103 and 104 can be an integralpiece forming the enclosure 102.

Disposed in the cavity 106 is a non-compressible material 108. Thenon-compressible material is preferably an elastomer, a liquid or acombination of elastomer and liquid. The non-compressible material, ifan elastomer, is preferably disposed in a length of extrusion having thecross-sectional profile 105 where individual compressive structuralelements 100 are sliced from the extrusion as a predetermined thickness.

The walls 104 are shaped such that a first compressive force 110, shownin FIG. 3A, tends to compress the structural element 100 by a firstdeflection 112 which causes an amplified second deflection 114 of thewalls 104 into the non-compressible material 108. The relaxed positionof the compressive structural element 100 (i.e., where no compressiveforce 110 is present) is shown in FIG. 3A as dashed lines. The walls 104thereupon exert a second compressive force 116 against thenon-compressible material 108 disposed in the cavity 106. Beingnon-compressible, the non-compressible material 108, resists the secondcompressive force with a resistive force 118 resulting in a resistanceto the first deflection 112 and the first compressive force 110.

In order to optimize the amplification of the second deflection 114, thewalls are preferably concavely shaped 120 into the cavity 106.Furthermore, the walls can be configured to provide optimum damping,optimum rigidity, or a combination of the two depending upon theapplication. For instance, as shown in FIGS. 1C and 3A, the walls 104can be of uniform thickness where the end portions 104a are ofsubstantially the same thickness as the center portion 104b. Thisconfiguration causes minimal migration of the non-compressible material108 due to the second compressive force 116 resulting in a compressivestructural element 100 which provides for some damping and highrigidity.

Alternatively, as shown in FIG. 6A, the walls 104 can be configured suchthat the center portion 104d is substantially thicker than at the endportions 104c. This configuration results in increased migration of thenon-compressible material 108 due to the second compressive force 116resulting in a compressive structural element 100 which provides somerigidity and high damping. It is appreciated by someone skilled in theart that the wall configuration can be varied to produce differingdegrees of desired damping and rigidity based upon the requirements ofthe application at hand.

It is also appreciated by someone skilled in the art that differentnon-compressible materials, or combinations of non-compressiblematerials will produce differing degrees of desired damping and rigiditybased upon the requirements of the application at hand. For instance, ahard elastomer will produce a more rigid structural element 100 withlittle damping, while a softer elastomer will produce a less rigidstructural element 100 with higher damping. Combining an elastomer witha liquid will result in still other possibilities regarding damping andrigidity.

Referring now to FIGS. 2A, 2B, 2C, and 3B, there is illustrated a secondembodiment of the present invention, namely, a tensile structuralelement referred to generally as reference numeral 200 and being similarto the compressive structural element 100 except for the element'sloading and wall configuration to provide damping and rigidity inresponse to the loading. The tensile structural element 200 has anenclosure 202 having walls 203, 204 and defining a cavity 206. Walls 204are again preferably formed by extruding the structural element'scross-sectional profile 205, as shown in FIG. 2C. Walls 203 arepreferably plates, formed by conventional methods, such as stamping, andfastened to the cross-sectional profile by conventional methods, such asspot welding. However, walls 203, 204 can be an integral piece formingthe enclosure 202.

Disposed in the cavity 206 is a non-compressible material 208. As withthe compressive structural element 100, the non-compressible material208 of the tensile compressive element 200 is preferably an elastomer, aliquid or a combination of elastomer and liquid. The walls 204 areshaped such that a tensile force 110, shown in FIG. 3B, tends toelongate the structural element 200 by a first deflection 212 whichcauses an amplified second deflection 214 of the walls 204 into thenon-compressible material 208. The relaxed position of the tensilestructural element 200 (i.e., where no tensile force is present) isshown in FIG. 3B as dashed lines. The walls 204 thereupon exert acompressive force 216 against the non-compressible material 208 disposedin the cavity 206. Being non-compressible, the non-compressible material208, resists the compressive force 216 with a resistive force 218resulting in a resistance to the first deflection 212 and the tensileforce 210.

In order to optimize the amplification of the second deflection 214, thewalls are preferably convexly shaped 220 away from the cavity 206. Asdiscussed previously with regard to the compressive structural element100, the walls 204 can be configured to provide optimum damping, optimumrigidity, or a combination of the two depending upon the application.For instance, as shown in FIGS. 2C and 3B, the walls 204 can be ofuniform thickness where the end portions 204a art of substantially thesame thickness as the center portion 204b. As discussed previously, thisconfiguration provides for some damping and high rigidity.

Alternatively, as shown in FIG. 6B, the walls 204 can be configured suchthat the center portion 204d is substantially thicker than at the endportions 204c. This configuration results in some rigidity and highdamping. As discussed above, it is appreciated by someone skilled in theart that the wall configuration can be varied to produce differingdegrees of desired damping and rigidity based upon the requirements ofthe application at hand.

As also discussed above, it is also appreciated by someone skilled inthe art that different non-compressible materials, or combinations ofnon-compressible materials will also produce differing degrees ofdesired damping and rigidity based upon the requirements of theapplication at hand.

In a third embodiment of the present invention, shown in FIGS. 4A, 4B,4C, 5A, and 5B, the structural elements of the first and secondembodiments are combined resulting in structural element 400. Thestructural element 400 has a compressive and a tensile structuralelement 100, 200, respectively. The compressive structural element 100has a first enclosure 402 having first walls 403, 404, and 405 anddefining a first cavity 406. The tensile structural element 200 has asecond enclosure 502 having second walls 403, 504, and 405 and defininga second cavity 506.

The first and second walls 404, 504, and 405 are preferably integrallyformed by extruding the structural element's cross-sectional profile505, as shown in FIG. 4C. First and second walls 403 are also preferablyintegrally formed as plates, by conventional methods, such as stamping,and fastened to the cross-sectional profile by conventional methods,such as welding.

Disposed in the first and second cavities 406, 506 are non-compressiblematerials 408, 508. The non-compressible materials are preferably anelastomer, a liquid or a combination of elastomer and liquid. The firstwalls 404, 405 are shaped such that a first force 410, shown in FIG. 5A,tending to compress the structural element 400 by a first deflection 412causes an amplified second deflection 414 of the first walls 404, 405into the first non-compressible material 408. The first walls 404, 405thereupon exert a first compressive force 416 against the firstnon-compressible material 408 disposed in the first cavity 406. Beingnon-compressible, the first non-compressible material 408, resists thefirst compressive force 416 with a resistive force 418 resulting in aresistance to the first deflection 412 and the first force 410.

The second walls 504, 405 are shaped such that a second force 510, shownin FIG. 5B, tending to elongate the structural element 400 by a thirddeflection 512 causes an amplified fourth deflection 514 of the secondwalls 504, 405 into the second non-compressible material 508. The secondwalls 504, 405 thereupon exert a second compressive force 516 againstthe second non-compressible material 508 disposed in the second cavity506. Being non-compressible, the second non-compressible material 508,resists the second compressive force 516 with a resistive force 518resulting in a resistance to the third deflection 512 and the secondforce 510.

Therefore, while in compression due to the first force 410 thestructural element 400 acts as does the compressive structural element100. While in tension due to the second force 510, the structuralelement 400 acts as does the tensile structural element 200.

In order to optimize the amplification of the second deflection 414, thefirst walls are preferably concavely shaped 420 into the first cavity406. Similarly, in order to optimize the amplification of the fourthdeflection 514, the second walls are preferably convexly shaped 520 awayfrom the second cavity 506. In the preferred configuration shown in FIG.4C one of the first walls surrounding the first cavity 406 alsocomprises one of the second walls surrounding the second cavity 506resulting in a shared wall 405.

Furthermore, as discussed above with regard to the compressive andtensile structural elements 100, 200 the walls and non-compressivematerials can be configured to provide optimum damping, optimumrigidity, or a combination of the two depending upon the application.However, the combined structural element 400 can be configured fordiffering characteristics for resistance to tensile forces andcompressive forces. For instance, the structural element can beconfigured to provide optimum rigidity and low damping in response to acompressive force, and high damping and low rigidity in response to atensile force.

Configuration of the structural element 400 is achieved as discussedabove by providing uniform wall thickness 404a, 404b, 405a, 405b, 504a,504b, as shown in FIG. 4C, by providing varying wall thickness 404c,404d, 504c, 504d, as shown in FIG. 6C, and/or by varying the types ofnon-compressible materials as well as their characteristics.

Referring now to FIGS. 7A, 7B, and 7C there is shown a fourth embodimentof the present invention generally referred to as reference numeral 700which is similar to the compressive structural element 100 except thatthe compressive structural element 700 is cylindrical in shape. Thecompressive structural element 700 has a cylindrical enclosure 702having a wall 704, a top 706, a bottom 708 and a cavity 710 defined bythe wall 704, top 706, and bottom 708. The top 706 and bottom 708 of thecompressive structural element 700 are separated by a height 712. Thecompressive structural element 700 also having a non-compressiblematerial 714 disposed in the cavity 710.

The wall 704 preferably comprises a plurality of panels 720 separated byflectural joints 718 for aiding the deflection of the wall 704 into thecavity 710. The flectural joints are preferably "in-turned" portionsrunning longitudinally to the structural elements height. Also, the wall704, top 706, and bottom 708 preferably comprise an integral metal shell722. However, it is appreciated by someone skilled in the art that anysuitable material can be utilized without departing from the scope andspirit of the invention.

The operation of compressive element 700 in response to a firstcompressive force will now be explained with reference to FIG. 3A inwhich the cross-sectional profile shown for compressive structuralelement 100 is similar to that of compressive structural element 700,the operation of both therefore being the same. The wall 704 ofcompressive element 700 are concavely shaped 716 such that a firstcompressive force tending to decrease the height 712 causes an amplifieddeflection of the wall 704 into the non-compressible material 714. As aresult, the wall 704 exerts a second compressive force against thenon-compressible material 714, resulting in a resistance to theamplified deflection and the first compressive force.

As discussed previously, the non-compressible material is preferably anelastomer, a liquid, or a combination of elastomer and liquid. Likecompressive element 100, compressive element 700 can be configured witha wall 704 for either optimum damping, optimum rigidity or anycombination of the two. This is achieved as discussed previously byproviding uniform wall thickness 704a, 704b, varying wall thickness (assimilarly shown in FIG. 6A), and by varying the type and characteristicsof the non-compressible material 714.

Referring now to FIGS. 8A, 8B, and 8C there is shown a fifth embodimentof the present invention generally referred to as reference numeral 800which is similar to tensile structural element 200 except thatcompressive structural element 800 is cylindrical in shape. Compressivestructural element 800 has a cylindrical enclosure 802 having a wall804, a top 806, a bottom 808 and a cavity 810 defined by the wall 804,top 806, and bottom 808. The top 806 and bottom 808 of the compressivestructural element 800 being separated by a height 812. The tensilestructural element 800 also having a non-compressible material 814disposed in the cavity 810.

The wall 804 preferably comprises a plurality of panels 820 separated byflectural joints 818 for aiding the deflection of the wall 804 into thecavity 810. The flectural joints are preferably "in-turned" portionsrunning longitudinally to the structural element's height 812. Also, thewall 804, top 806, and bottom 808 preferably comprise an integral metalshell 822. However, it is appreciated by someone skilled in the art thatany suitable material can be utilized without departing from the scopeand spirit of the invention.

The operation of compressive element 800 in response to a tensile forcewill now be explained with reference to FIG. 3B in which thecross-sectional profile shown for tensile structural element 200 issimilar to that of tensile structural element 800, the operation of boththerefore being the same. The wall 804 of compressive element 800 isconvexly shaped 816 such that a tensile force tending to increase theheight 812 causes an amplified deflection of the wall 804 into thenon-compressible material 814. As a result, the wall 804 exerts acompressive force against the non-compressible material 814, resultingin a resistance to the amplified deflection and the tensile force.

As discussed previously, the non-compressible material is preferably anelastomer, a liquid, or a combination of elastomer and liquid. Liketensile element 200, tensile element 800 can be configured with a wall804 for either optimum damping, optimum rigidity or any combination ofthe two. This is achieved as discussed previously by providing uniformwall thickness 804a, 804b, varying wall thickness (as similarly shown inFIG. 6B), and by varying the type and characteristics of thenon-compressible material 814.

Embodiments of the present invention which utilize the tensile andcompressive structural elements 100, 200, and 400 previously discussedwill now be described. Referring now to FIGS. 9A, 9B, and 9C, there isillustrated a structural beam generally referred to as reference numeral900. The structural beam 900 has an upper surface 902 in compression anda lower surface 904 in tension due to a loading force 906. A web 908connects the upper surface to the lower surface in a typical I-beamconfiguration. However, it is appreciated by someone skilled in the artthat beam configurations other than that of an I-beam can be utilizedwithout departing from the spirit and scope of the invention.

A plurality of compressive structural elements 100 are disposed alongthe length of the upper surface 902. A plurality of tensile structuralelements 200 are disposed along the length of the lower surface 904. Thestructural elements 100, 200 are fastened to their respective surfaces902, 904 by conventional methods. If the enclosures and beam are metal,the structural elements 100, 200 are preferably welded. However, anyconventional fastening method can be utilized, such as epoxy bonding orfastening with screws or rivets.

The compressive structural elements 100 on the upper surface 902 and thetensile structural elements 200 on the lower surface 904 provide eitherdamping or added rigidity to the beam as a result to their resistance tothe loading force 906. As discussed previously, the structural elements100, 200 can be configured for optimum damping, rigidity, or anycombination thereof.

Referring now to FIGS. 10A, 10B, and 10C, there is illustrated astructural beam generally referred to as reference numeral 1000. Thestructural beam 1000, like beam 900 has an upper surface 1002 incompression and a lower surface 1004 in tension due to a loading force1006. A web 1008 connects the upper surface to the lower surface in atypical I-beam configuration. However, it is appreciated by someoneskilled in the art that beam configurations other than that of an I-beamcan be utilized without departing from the spirit and scope of theinvention.

A plurality of combined structural elements 400 are disposed along thelength of the upper and lower surfaces 1002, 1004. As discussedpreviously, the structural elements 400 are fastened to the upper andlower surfaces 1002, 1004 by conventional methods.

The combined structural elements 400 on the upper and lower surfaces1002, 1004 provide either damping or added rigidity to the beam as aresult to their resistance to t he loading force 906. As discussedpreviously, the structural elements 100, 200 can be configured foroptimum damping, rigidity, or any combination thereof. However, unlikestructural beam 900, structural beam 1000 is equipped to provide dampingand/or added rigidity to the loading force 1006 in the direction shown,or a loading force in the opposite direction in which the upper surface1002 is in tension and the lower surface 1004 is in compression.Structural beam 1000 therefore being more versatile than structural beam900 which is utilized in situations where the loading force is known notto vary in direction, or where the damping and added rigidity is onlydesired when the loading force is in a certain direction.

Referring now to FIGS. 11A and 11B there is illustrated a sixthembodiment of the present invention in which a structural beam is shownand generally referred to by reference numeral 1100. The structural beam1100 has an upper surface 1102, a lower surface 1104 and first andsecond walls 1106, 1108, respectively, connecting the upper surface 1102to the lower surface 1104. The volume between the walls 1106, 1108define a cavity 1110 in which a non-compressible material 1112 isdisposed.

The beams cross-sectional profile, shown in FIG. 11B is preferablyfabricated by an extrusion process. The cavity 1110 is preferablysubsequently filled with non-compressible material 1112 by any methodknown in the art, such as injecting an elastomer in a liquid state. Asdiscussed previously, with regard to the other embodiments of thepresent invention the non-compressible material 1112 is preferably anelastomer, a liquid, or any combination thereof.

Similar to the compressive element 100, walls 1106, 1108 are shaped suchthat a first compressive force tending to compress the beam 1100 by afirst compression causes an amplified second deflection of the walls1106, 1108 into the non-compressible material 1112, resulting in aresistance to the first deflection and the force tending to compress thebeam 1100. The force tending to compress the beam 1100 being a loadingforce 1116. Preferably, the beam 1100 has a typical I-Beam configurationwith walls that are concavely shaped 1114 to optimize the deflectioninto the non-compressible material 1112.

As discussed previously with regard to the previous embodiments, thebeam 1100 can be configured for optimum damping, rigidity, or acombination thereof by varying the wall thickness 1108a, 1108b and/or byvarying the type and characteristics of the non-compressible material1112.

Embodiments of the present invention which utilize the tensile andcompressive structural elements 700 and 800 previously described willnow be described. Referring now to FIGS. 12A and 12B, there isillustrated a structural beam generally referred to by reference numeral1200. The structural beam having a cross-sectional profile 1202, withfirst portions 1204 of the profile being in compression and secondportions 1206 being in tension due to a loading force 1208. Thestructural beam is preferably configured as an I-Beam having an upperflange 1210 in compression, a lower flange 1212 in tension, and a web1214 connecting the upper flange 1210 to the lower flange 1212. Portionsof greatest compression 1216 occur in the upper flange 1210, andportions of greatest tension 1218 occur in the lower flange 1212. It isunderstood to someone skilled in the art that the beam can havedifferent cross-sectional profiles and not depart from the scope andspirit of the present invention.

The beam profile 1202 has a multiplicity of compressive structuralelements 700 disposed in portions of compression 1204. Preferably, thecompressive structural elements 700 are of greater incidence in portionsof greatest compression 1216. The beam profile 1202 also having amultiplicity of tensile structural elements 800 disposed in portions oftension 1206. Preferably, the tensile structural elements 800 are ofgreater incidence in portions of greatest tension 1218. The compressiveand tensile structural elements 700, 800 provide damping and/or rigidityin response to the loading force.

The structural elements can be configured, as discussed previously, foroptimum damping, rigidity, or any combination thereof by varying thewall thickness and/or the type and characteristics of thenon-compressible materials.

Referring now to FIGS. 13A and 13B there is illustrated a structuralbeam generally referred to by reference numeral 1300. The structuralbeam having a cross-sectional profile 1302, with first portions 1304 ofthe profile being in compression and second portions 1306 being intension due to a loading force 1308. The structural beam is preferablyconfigured as an I-Beam having an upper flange 1310 in compression, alower flange 1312 in tension, and a web 1314 connecting the upper flange1310 to the lower flange 1312. Portions of greatest compression 1316occur in the upper flange 1310, and portions of greatest tension 1318occur in the lower flange 1312. It is understood to someone skilled inthe art that the beam can have different cross-sectional profiles andnot depart from the scope and spirit of the present invention.

The beam profile 1302 has a multiplicity of compressive and tensilestructural elements 700,800 joined together and disposed in portions ofcompression and tension 1304 and 1306. Preferably, the joined structuralelements 700,800 are of greater incidence in portions of greatestcompression 1316 and greatest tension 1318.

The joined structural elements 700,800 can be configured, as discussedpreviously, for optimum damping, rigidity, or any combination thereof byvarying the wall thickness and/or the type and characteristics of thenon-compressible materials.

The combined structural elements 700,800 provide either damping or addedrigidity to the beam as a result of their resistance to the loadingforce 1308. As discussed previously, the structural elements 700, 800can be configured for optimum damping, rigidity, or any combinationthereof. However, unlike structural beam 1200, structural beam 1300 isequipped to provide damping and/or added rigidity to the loading force1308 in the direction shown, or a loading force in the oppositedirection in which the upper flange 1310 is in tension and the lowerflange 1312 is in compression. Structural beam 1300 therefore being moreversatile than structural beam 1200 which is utilized in situationswhere the loading force is known not to vary in direction, or where thedamping and/or added rigidity is only desired when the loading force isin a certain direction.

Further embodiments of the present invention which utilize thecompressive and tensile structural elements 700,800 previously discussedwill now be described in relation to motion impartation devices.Referring now to FIGS. 14A and 14B, there is illustrated a coupling 1400for imparting rotation (and torque) from a driving shaft 1402 to adriven shaft 1404. The driving shaft 1402 is connected to a drivingportion 1406 of the coupling 1400 and the driven shaft 1404 is connectedto a driven portion 1408 of the coupling 1400.

The driving portion 1406 is engaged with the driven portion 1408 suchthat a gap 1410 exists between driven and driving portions 1406, 1408.Preferably, the driven and driving portions 1406, 1408 comprise aplurality of teeth 1406a, 1408a which are meshed together with the gap1410 being between each driving and driven teeth 1406a, 1408a,respectively. Disposed in each gap 1410 is a structural element.

Rotation of the driving portion 1406 results in a compressive forcebeing exerted on the driven portion 1408. In the configuration shown inFIG. 14B, where a plurality of driven and driving teeth 1406a, 1408a areutilized, each driving tooth 1406a exerts a compressive force on thestructural element disposed between it and the next driven tooth 1408ain the direction of the rotation. Simultaneously, each driven tooth1408a exerts a tensile force on the structural element disposed betweenit and the next driving tooth 1406a in the direction opposite to thedirection of rotation. Thus, the structural elements disposed in thegaps 1410 provide damping and/or rigidity in response to the drivingrotation (and torque) depending upon the structural element'sconfiguration as previously discussed.

Preferably joined compressive and structural elements 700,800 aredisposed in the gaps 1410 for added versatility, i.e, for the desireddamping and/or rigidity in either direction of rotation. However, allcompressive 700 or all tensile 800 structural elements can be used.However, only half of them would be effectively working in any onedirection of rotation, with the other half working in the oppositedirection of rotation. Another alternative, is to alternate compressive700 and tensile 800 elements in the gaps 1410. However, this arrangementcan only be used if the direction of rotation is known and if it doesnot vary.

The motion impartation device previously discussed can also be adaptedto provide damping and/or rigidity in response to forces exerted whenimparting translation, or linear motion from a driving portion to adriven portion. Such a device is illustrated in FIG. 15 and generallyreferred to by reference numeral 1500. FIG. 15 illustrates a linearcoupling 1500 for imparting motion from a driving portion 1502 to adriving portion 1504. Like the rotational coupling 1400, the driving anddriven portions 1502, 1504 preferably comprise driven and driving teeth1502a, 1504a separated by gaps 1510 in which structural elements aredisposed. The remainder of the linear coupling in principle andstructure is the same as the rotational coupling 1400 previouslydescribed.

Methods for fabricating the structural beams 1200, 1300 previouslydiscussed will now be described. Illustrated in FIG. 16 is a flow chartshowing the steps for fabricating structural beam 1200, the methodgenerally referred to by reference numeral 1600. At step 1610 and 1620,respectively, compressive and tensile structural elements 700, 800 areprovided.

Preferably the providing steps 1610, 1620 are accomplished byfabricating the first and second non-compressible material to a shapeand size similar to that of the first and second cavities. Thenon-compressible materials can be fabricated by any conventional meansknown in the art, such as injection molding. The first and secondenclosures are then formed around the non-compressible material by anymeans known in the art, preferably by either dipping the elastomers intoa liquid material to form a shell enclosure or by spraying a moltenmaterial onto the non-compressible materials to form a shell. Both ofthese methods require molten shell materials which have a melting pointlower than that of the non-compressible material so that thenon-compressible material is not damaged or melted during the enclosureforming process. In a subsequent operation, flectural joints can becreated by a stamping operation.

An alternative method for providing 1610, 1620 the compressive andtensile structural elements 700, 800 comprises forming the first andsecond enclosures and then filling the enclosures with first and secondnon-compressible materials, respectively. The forming of the enclosurescan be done by any means known in the art, such as casting, metalforming, or injection molding. The filling of the enclosures can also bedone by any means known in the art, such as by injecting a liquidmaterial into the enclosure and allowing it to solidify.

The next step in the fabrication process 1600 is to form thecross-sectional profile of the beam at step 1630. This is accomplishedby conventional processes known in the art, such as by extrusion orcasting. Lastly, at step 1640 the multiplicity of compressive andtensile structural elements 700, 800 are disposed throughout the beamcross-section and along the length of the extrusion. Preferably, thedisposing step 1640 includes the sub-steps of weighting the greatestincidence of compressive structural elements in portions of greatestcompression (step 1640a) and weighting the greatest incidence of tensilestructural elements in portions of greatest tension (at step 1640b).

The weighing steps 1640a, 1640b can be accomplished by providing a wax,or similar material, extrusion or cast of the beam and positioning thecompressive and tensile structural elements 700, 800 within the wax inareas of greatest compression and greatest tension, respectively. Thebeam is then cast by adding liquid material, preferably metal, to thecast such that the liquid material replaces the wax and the structuralelements remain positioned in the portions of greatest compression andtension. If the structural elements are denser than the wax and the waxis sufficiently soft, then the positioning can be accomplished byinserting the structural elements into the wax and subjecting the waxbeam to a centrifugal force such that the centrifugal force exerted onthe elements causes them to relocate to positions along thecross-sectional profile corresponding to portions of greatest tensionand compression.

Alternatively, the weighting steps 1640a, 1640b can also be accomplishedby stringing the compressive structural elements 700 together along anaxis parallel to their walls (i.e., top to bottom), stringing thetensile structural elements 800 together in a similar fashion,positioning the element strings in portions of greatest compression andgreatest tension, and casting or extruding the beam profile around theelement strings such that they remain as positioned. The elements arepreferably strung together by wiring the top of an element to asuccessive bottom of another element. Alternatively, the elements can bewelded together.

Referring now to FIG. 17, there is illustrated a method for fabricatingstructural beam 1300 generally referred to by reference numeral 1700.The method illustrated in FIG. 17 in which all steps similar to oridentical with those in FIG. 16 are designated with the same referencenumerals, is merely modified with regard to the previous method, in thatthe structural elements 700, 800 are joined at step 1710 to form acombined structural element. The joining is preferably accomplished bywelding the structural elements together to form a shared wall.

Also, modified with regard to the previous method is the weighting stepwhich only comprises weighting the combined structural elementthroughout the beam profile, instead of weighting each structuralelement as is done in the previous method. The preferable methods forweighting of the elements and positioning the elements as discussed inthe previous method are likewise the same.

From the foregoing, it becomes readily apparent to one skilled in theart that the novel structural elements of the present invention offersincreased rigidity and damping over currently employed devices. Due tothe inventive structural element configuration, the advantages offeredby the inventive structure resides in:

(a) because the walls of the structural elements can be made relativelythin, and because the non-compressible material is relativelylightweight, the structural element can be made very lightweight;

(b) because of the novel configuration whereby the non-compressiblematerial resists any loading forces, the structural element can beconfigured for high rigidity;

(c) because of the novel configuration, the structural element can alsoprovide high internal damping by configuring the walls to provide for anincreased migration of non-compressible material within the cavity; and

(d) because of its lightweight, high rigidity, and high internal dampingcharacteristics, the structural element of the present inventionprovides a reliable, low cost alternative to active damping devices.

While there has been shown and described what is considered to bepreferred embodiments of the invention, it will, of course, beunderstood that various modifications and changes in form or detailcould readily be made without departing from the spirit of theinvention. It is therefore intended that the invention be not limited tothe exact forms described and illustrated, but should be constructed tocover all modifications that may fall within the scope of the appendedclaims.

I claim:
 1. A method for fabricating a structural beam having across-sectional profile, first portions of the profile being incompression and second portions of the profile being in tension due to aloading force, the beam also having compressive and tensile structuralelements, each compressive structural element comprising a firstenclosure having a first wall and one or more second walls surrounding afirst cavity, and a first non-compressible material disposed in thefirst cavity, wherein the one or more second walls each having at leasta portion thereof inwardly shaped towards the first cavity such that theloading force acting on the first wall tends to compress the compressivestructural element by a first deflection causing an amplified seconddeflection, relative to the first deflection, of the one or more secondwalls into the first non-compressible material, thereby exerting acompressive force due to the second deflection against the firstnon-compressible material, resulting in a resistance to the firstdeflection and the loading force, and each tensile element comprising asecond enclosure having a third and one or more fourth walls surroundinga second cavity, and a second non-compressible material disposed in thesecond cavity, wherein the one or more fourth walls each having at leasta portion thereof outwardly shaped away from the second cavity such thatthe loading force acting on the third wall tends to elongate the tensilestructural element by a third deflection causing an amplified fourthdeflection, relative to the third deflection, of the one or more fourthwalls into the second non-compressible material, thereby exerting acompressive force due to the fourth deflection against the secondnon-compressible material, resulting in a resistance to the thirddeflection and the loading force, the method comprising the stepsof;providing the compressive structural elements; providing the tensilestructural elements; forming the beam having the cross-sectional profilefor a predetermined length; and during the forming step, disposing amultiplicity of the compressive and tensile structural elementsthroughout the beam cross-sectional profile and along the predeterminedlength.
 2. The method of claim 1, wherein the providing steps furtherinclude the sub-steps of:fabricating the first non-compressible materialto a shape and size substantially similar to that of the first cavity;fabricating the second non-compressible material to a shape and sizesubstantially similar to that of the second cavity; forming the firstenclosures having the first and one or more fourth walls, around thefirst non-compressible material; and forming the second enclosureshaving third and one or more fourth walls, around the secondnon-compressible material.
 3. The method of claim 2, wherein the stepsof fabricating the first and second non-compressible materials areperformed by injection molding, wherein the non-compressible material isan elastomer.
 4. The method of claim 2, wherein the steps of forming thefirst and second enclosures around their respective first and secondnon-compressible materials are performed by spraying a metal shell ontothe first and second non-compressible materials.
 5. The method of claim2, wherein the steps of forming the first and second enclosures aroundtheir respective first and second non-compressible materials areperformed by dipping the elastomer into a liquid material bath whichhardens to form a shell around the first and second non-compressiblematerials.
 6. The method of claim 1, wherein the providing steps furtherinclude the sub-steps of:forming the first enclosure; forming the secondenclosure; filling the first enclosure with the first non-compressiblematerial; and filling the second enclosure with the secondnon-compressible material.
 7. The method of claim 1, wherein the step ofdisposing a multiplicity of the compressive and tensile structuralelements throughout the beam cross-sectional profile and along itslength further includes the sub-steps of:weighting the greatestincidence of compressive structural elements in portions of greatestcompression; and weighting the greatest incidence of tensile structuralelements in portions of greatest tension.
 8. The method of claim 7,wherein the weighting sub-steps comprise:providing a wax replica of thebeam; positioning the compressive and tensile structural elements withinthe wax replica in portions of greatest compression and greatesttension, respectively; casting the beam by adding liquid material to thewax replica such that the liquid material replaces the wax and thestructural elements remain positioned in the portions of greatestcompression and tension.
 9. The method of claim 8, wherein thepositioning sub-step is performed by subjecting the wax replica tocentrifugal force such that the centrifugal force exerted on thecompressive and tensile elements causes them to relocate to positionsalong the cross-sectional profile corresponding to portions of greatestcompression and portions of greatest tension, respectively.
 10. Themethod of claim 7, wherein the weighting sub-steps comprise:stringingthe compressive structural elements together along an axis parallel totheir first walls; stringing the tensile structural elements togetheralong an axis parallel to their third walls; positioning the compressiveand tensile structural element strings in areas of greatest portions ofcompression and tension, respectively; and casting the beam around thecompressive and tensile structural element strings such that they remainpositioned in areas of greatest compression and tension, respectively.11. The method of claim 10, wherein the stringing sub-step compriseswelding the elements together.
 12. The method of claim 10, wherein theforming step comprises casting the beam after the positioning step. 13.The method of claim 10, wherein the forming step comprises extruding thebeam, and where the extruding occurs simultaneous with the positioningstep.
 14. A method for fabricating a structural beam having across-sectional profile, first portions of the profile being incompression and second portions of the profile being in tension due to aloading force, the beam also having structural elements, each structuralelement comprising a compressive and tensile structural element, thecompressive structural element having a first enclosure having a firstwall and one or more second walls surrounding a first cavity, thetensile structural element having a second enclosure having a third walland one or more fourth walls surrounding a second cavity, a firstnon-compressible material disposed in the first cavity, and a secondnon-compressible material disposed in the second cavity, wherein the oneor more second walls each having at least a portion thereof inwardlyshaped towards the first cavity such that the loading force acting onthe first wall tends to compress the structural element by a firstdeflection causing an amplified second deflection, relative to the firstdeflection, of the one or more second walls into the firstnon-compressible material, thereby exerting a first compressive forceagainst the first non-compressible material, resulting in a resistanceto the first deflection and the loading force, and wherein the one ormore fourth walls each having at least a portion thereof outwardlyshaped away from the second cavity such that the loading force acting onthe third wall tends to elongate the structural element by a thirddeflection causing an amplified fourth deflection, relative to the thirddeflection, of the one or more fourth walls into the secondnon-compressible material, thereby exerting a second compressive forceagainst the second non-compressible material, resulting in a resistanceto the third deflection and the loading force, the method comprising thesteps of;providing the compressive structural elements; providing thetensile structural elements; joining the compressive and tensilestructural elements to form the structural elements; forming the beamhaving the cross-sectional profile for a predetermined length; andduring the forming step disposing a multiplicity of the structuralelements throughout the beam cross-sectional profile and along thepredetermined length.
 15. The method of claim 14, wherein the providingsteps further include the sub-steps of:fabricating the firstnon-compressible material to a shape and size substantially similar tothat of the first cavity; fabricating the second non-compressiblematerial to a shape and size substantially similar to that of the secondcavity; forming the first enclosure having the first and one or moresecond walls, around the first non-compressible material; and formingthe second enclosure having the third and one or more fourth walls,around the second non-compressible material.
 16. The method of claim 15,wherein the steps of fabricating the first and second non-compressiblematerials are performed by injection molding, wherein thenon-compressible material is an elastomer.
 17. The method of claim 15,wherein the steps of forming the first and second enclosures aroundtheir respective first and second non-compressible materials areperformed by spraying a metal shell onto the first and secondnon-compressible materials.
 18. The method of claim 15, wherein thesteps of forming the first and second enclosures around their respectivefirst and second non-compressible materials are performed by dipping theelastomer into a liquid material bath which hardens to form a shellaround the first and second non-compressible materials.
 19. The methodof claim 14, wherein the providing steps further include the sub-stepsof:forming the first enclosure; forming the second enclosure; fillingthe first enclosure with the first non-compressible material; andfilling the second enclosure with the second non-compressible material.20. The method of claim 14, wherein the step of disposing a multiplicityof the structural elements throughout the beam cross-sectional profileand along its length further includes the sub-step of weighting thegreatest incidence of structural elements in portions of greatestcompression and greatest tension.
 21. The method of claim 20, whereinthe weighting sub-steps comprise:providing a wax replica of the beam;positioning the compressive and tensile structural elements within thewax replica in portions of greatest compression and greatest tension,respectively; casting the beam by adding liquid material to the waxreplica such that the liquid material replaces the wax and leaves thestructural elements in their positions.
 22. The method of claim 21,wherein the positioning sub-step is performed by subjecting the waxreplica to centrifugal force such that the centrifugal force exerted onthe compressive and tensile elements causes them to relocate topositions along the cross-sectional profile corresponding to portions ofgreatest compression and portions of greatest tension, respectively. 23.The method of claim 20, wherein the weighting sub-stepscomprise:stringing the compressive structural elements together along anaxis parallel to their first walls; stringing the tensile structuralelements together along an axis parallel to their third walls;positioning the compressive and tensile structural element strings inareas of greatest portions of compression and tension, respectively; andforming the beam around the compressive and tensile structural elementstrings such that they remain in areas of greatest compression andtension, respectively.
 24. The method of claim 23, wherein the stringingsub-step comprises welding the elements together.
 25. The method ofclaim 23, wherein the forming step comprises casting the beam after thepositioning step.
 26. The method of claim 23, wherein the forming stepcomprises extruding the beam, and where the extruding occurssimultaneous with the positioning step.
 27. The method of claim 14,wherein the joining step comprises welding the compressive and tensilestructural elements together to form a common wall.